Which approaches could I use to create a simple chatbot using a neural network?
I would recommend to start by reading this blogpost.
You can probably cannibalise the code to create a RNN that takes in one statement of a dialogue and then proceeds to output the answer to that statement.

That would be the easy version of your project, all without word vectors and thought vectors. You are just inputting characters, so typos don't need to concern you.

The next more complex step would be to input word vectors instead of characters. That would allow you to generalise to words that aren't part of your training data. And it is probably still just a minor modification of the code. 

If you insist on using thought vectors, you should start reading up on NN translation. And probably try to get a pre-trained encoder network. Or pre-train it yourself on a large translation corpus for your language. 

With your small training set the best you can do is probably massively overfit until your system recreates your training data verbatim. Using word vectors will allow your system to give the same answer to "I beat the cat today." as you gave in the training data to "I kicked the dog yesterday." 

I'm not sure thought vectors will make a big difference. If you get the decoder to learn at all.